NEW PHASE-TRANSITION IN AN EASY-AXIS TRIANGULAR ANTIFERROMAGNET

The NMR of Mn-55 in the quasi-one-dimensional noncollinear antiferroma gnet CsMnI3 is investigated at T = 1.3 K in magnetic fields up to simi lar to 80 kOe and angles between the field and C-6 axis phi approximat e to 0.5 degrees and phi = 7 degrees. A new reorientational magnetic p hase transition is observed in a field H-cl approximate to 39.0 kOe. T he magnetic structure for H > H-cl is determined. The average Mn2+ spi ns of the magnetic sublattices in the new phase are determined from an analysis of the NMR spectrum to be [S-C] = 1.63 and [SD] = 1.72. (C) 1998 American Institute of Physics.